The vision for a $1.5 billion medical, residential and commercial complex at U.S. 95 and Galleria Drive took its first major step toward becoming a reality Tuesday night when the Henderson City Council finalized the sale of a 151-acre plot to developers.

The sale of the city-owned plot to Union Village LLC and its partners for $11.6 million officially sets in motion the next phase of the planned development, which would be anchored by a hospital and senior retirement community.

David Baker, a partner and developer in the project, said the next steps will involve conducting various engineering and environmental studies on the site.

“This allows us to move forward in a big way,” he said. “You can’t go forward until you know you have a deal.”

The sale was passed unanimously as part of the council’s consent agenda, which Baker attributed to planning and the amount of buy-in the project had garnered.

In the works for more than a year, the Union Village plans were first unveiled to the public in April. Described as an “integrated health village,” the mixed-use development will be centered on a state of-the-art Rose de Lima Campus operated by St. Rose Dominican Hospitals.

Residential apartments, a midrange hotel, restaurants, retail and medical offices are all also included in the plans.

The city retained five acres of the plot to house the planned $63 million Henderson Space and Science Center, which is being developed separately.

Originally appraised at $30.1 million, the land was sold at a discount because developers will have to pay $17.5 million for grading work on a large gravel pit at the site before construction can begin.

The city will begin filling the pit in the next few months after authorizing $4.6 million for the work in November.

Baker said construction on the site is slated to start sometime between December and April of next year. The first phase, including the hospital and senior community, is expected to be finished in four years, with further expansion happening over the following four years.